Sometimes it starts good and sometimes won't start

I would also check negative battery cable. I have had a few vehicles that needed them. Pretty cheap to replace.

If starter doesn't spin everytime. Clean battery terminals and a connection. Check connection at starter. Try putting into neutral to start. If starter still doesn't turn car over everytime. Probably starter solenoid. If starter spins every time and doesn't start check temperature sensor. My car once started only when sitting for a couple of hours. Because sensor was saying it was really cold and it would flood it. Had to push gas peddle to floor and hold it there until started. If that is the case change temperature sensor. If car is after mid 90s take and get it scanned.